What is diabetic retinopathy
Diabetic retinopathy is a serious complication of diabetes that damages the blood vessels of the retina. It is the leading cause of blindness in working-age adults (20–64 years) in developed countries.
The retina is a layer of nerve tissue lining the back of the eye: this is where light stimuli are converted into nerve signals and sent to the brain. The health of the retina depends on a dense network of blood capillaries that nourish it.
Long-term high blood sugar makes these capillaries fragile and leaky: microaneurysms form and leak fluid and proteins, some vessels become blocked and — in the advanced stages — the eye responds to low oxygen (hypoxia) by stimulating the growth of new abnormal vessels (neovascularisation).
A central complication is diabetic macular oedema, in which fluid builds up in the macula, impairing sharp vision. It is the main cause of declining vision in patients with diabetes.
- What it affects
- The blood vessels of the retina and, often, the macula.
- Main cause
- Chronic hyperglycaemia that gradually damages the retinal capillaries.
- Key feature
- Progressive and silent in its early stages — symptoms appear when the damage is already advanced.
- Who is at risk
- Everyone with diabetes, with risk increasing after 15–20 years of disease.
How it progresses
Diabetic retinopathy progresses in stages, from minor capillary changes to the proliferative form with abnormal new vessels. Early recognition is crucial because many lesions, once established, are irreversible.
The silent trap
The disease can progress for years without any symptoms: the patient continues to see well until the damage reaches the macula or a sudden vitreous haemorrhage occurs. At that point, vision loss can be severe and in part cannot be recovered.
The different types
Diabetic retinopathy is classified according to the **severity of the vascular damage** and whether or not neovascularisation is present. Each stage requires different treatment strategies. Diabetic macular oedema, a central complication that can occur at any stage, is also included.
- 01
Mild non-proliferative retinopathy
Early formThis is the early form of the disease. The first damage to the retinal capillaries appears as small bulges called microaneurysms and as pinpoint haemorrhages. Yellowish deposits of lipids and proteins also appear, known as hard exudates.
At this stage the patient feels no symptoms: diagnosis is possible only through an eye examination with pupil dilation. For this reason, regular check-ups are recommended for everyone with diabetes, even without symptoms.
Non-proliferative retinopathy — microaneurysms and exudates Features
- Microaneurysms and small pinpoint haemorrhages
- Hard exudates (deposits of lipids and proteins)
- Often completely asymptomatic
- 02
Moderate-to-severe non-proliferative retinopathy
Pre-proliferativeThe number and extent of haemorrhages and exudates increase. Some capillaries become blocked, depriving areas of the retina of the oxygen they need. Venous abnormalities appear, as do areas of retinal ischaemia.
When the ischaemia affects the macula or is associated with diabetic macular oedema, the first problems with central vision begin: difficulty reading, reduced visual acuity, slight distortion. Without treatment, this form can progress rapidly to the proliferative form.
This is the stage at which timely treatment — with control of diabetes, anti-VEGF injections if macular oedema is present, and focal laser — can greatly slow progression and protect sight.
- 03
Proliferative retinopathy
Advanced formThis is the most serious form. The eye responds to low oxygen (hypoxia) by stimulating the growth of new blood vessels (neovascularisation), but these vessels are abnormal and fragile: they break easily, causing vitreous haemorrhage and forming scar tissue that can pull on the retina until it detaches.
Without treatment, it can lead to severe loss of sight or blindness. It requires immediate treatment with panretinal laser photocoagulation, intravitreal injections and — in the more complex cases — vitrectomy.
Proliferative form — abnormal neovessels and haemorrhages Warning signs
- Sudden appearance of floaters or threads
- A dark veil or patch in your field of vision
- Sudden drop in visual acuity
- Flashes of light (photopsia)
- 04
Diabetic macular oedema
Central complicationDiabetic macular oedema is a complication that can occur at any stage of retinopathy, even in mild non-proliferative forms. It occurs when fluid that has leaked from damaged capillaries builds up in the macula, the central area of the retina responsible for fine vision.
It is the main cause of declining vision in patients with diabetes. The first-choice treatment is intravitreal anti-VEGF injections; in selected cases, focal laser and corticosteroids are used.
To detect macular oedema even in the early stages, OCT (optical coherence tomography) is the essential diagnostic test: it shows the thickness of the retina with micrometre precision.
Why early diagnosis is crucial
Diabetic retinopathy is a condition that is silent in its early stages: the patient continues to see well while the damage progresses. When symptoms appear — declining vision, distortion, dark patches — the damage has often already become established and is partly irreversible.
For this reason, everyone with diabetes must have an eye examination with dilation at least once a year, even without symptoms. For type 1 diabetes, the first check should take place within 5 years of diagnosis; for type 2, immediately at diagnosis. Pregnant women with diabetes must have a check in the first trimester.
Timely diagnosis, combined with optimal control of blood sugar, blood pressure and cholesterol, is today the most effective tool for preventing vision loss.